Rescue/evacuation self-testing system for traction elevators

ABSTRACT

A monitoring system for controlling self-testing of a traction elevator includes a self-testing process module in communication with a three-phase AC back-up battery power supply. The self-testing process module includes a processor configured to initiate and control a series of steps for performing measurements of the three-phase AC back-up battery power supply, including measurements of the battery supply during a simulated emergency situation (“rescue/evacuation”). The processor is programmed to initiate testing on a defined schedule and transmit test results to a maintenance system (including remotely-located systems) on a routine basis. The monitoring system also includes a display unit providing visual information regarding the status of self-testing processes and their results and a communications unit for transmitting test results to a remote maintenance controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.16/208,702, filed Dec. 4, 2018 and incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to traction elevator systems and, moreparticularly, to a system for performing self-testing procedures on atraction elevator to ensure proper operation in the event of a powerfailure.

BACKGROUND OF THE INVENTION

A back-up power supply system is used to raise or lower an elevator carto the nearest available floor during an emergency loss of main power.The back-up power supply system stores enough energy to move the car andopen the doors to eliminate any entrapment of passengers (also referredto as a “rescue/evacuation” operation).

Preferably, the back-up power supply system delivers three-phase ACpower (480 VAC, 400 VAC, or in the range of 208-240 VAC depending on theelevator system requirements). The three-phase AC power output of aback-up power supply system is typically in the range of 1-8 kVa, whichis considered sufficient to energize the traction elevator controller,variable frequency (VF) drive, brakes, and door motors. A typical systemutilizes a stack of four batteries (a “stack” meaning a seriesconnection of separate batteries) to provide three-phase AC back-uppower.

An important aspect of providing back-up power supply system is ensuringthat the system is fully charged and in operable condition. Some priorart systems for performing checks require a technician to interact withthe unit and provide testing in a manual state, thus depending on theskill of the technician and a defined maintenance schedule to recognizeproblems before a need arises to use the back-up system. Problems suchas a weak battery or completely discharged battery cell, impact theability of the traction elevator to function as necessary in anemergency situation. Besides problems with the power level in theback-up supply, problems with the elevator car's actualrescue/evacuation system may go undiagnosed until an actual emergencyoccurs.

Many prior art systems have been configured to monitor only a DC outputpower of individual battery cells, which is not considered to be areliable indicator of the performance of a three-phase AC back-up powersupply when being used to perform rescue/evacuation operations.

SUMMARY OF THE INVENTION

The needs remaining in the art are addressed by the present invention,which relates to traction elevator systems and, more particularly, to asystem for performing automated and scheduled self-testing of athree-phase AC back-up power supply of a traction elevator, includingboth self-testing of the three-phase AC power supply itself and at timesthe operation of the traction elevator during rescue/evacuationprocedures, to ensure proper operation of the traction elevator in theevent of a power failure.

In accordance with the principles of the present invention, a monitoringsystem is utilized in conjunction with a three-phase AC back-up powersupply (and elevator control apparatus) to initiate self-testing of thepower supply on a regular schedule and maintain a record of the testresults. The self-testing of the power supply includes testing of theindividual battery cells used to generate the three-phase AC back-uppower, as well as the circuitry used to perform the DC to AC conversionfrom the batteries to the back-up power supply output. The use of athree-phase AC back-up power supply (instead of a single phase back up,which is common) is considered to be an optimum choice, inasmuch as theamount of available power from a three-phase AC system is able to notonly control the motor of the traction elevator to bring the car to thenearest floor in a timely manner, but also provide sufficient power tothe braking system and motor controls for the door. The results may alsobe sent to a remotely-located maintenance controller (via wired orwireless communication) and provide an alert about any problems thatneed to be immediately addressed. In an exemplary embodiment of thepresent invention, the self-testing further includes performing arescue/evacuation process of the elevator car itself (i.e., powering theelevator motor with the three-phase AC back-up power supply to move toan appropriate floor and cycle through a door open/close sequence). Theresults of the rescue/evacuation self-test are similarly stored andtransmitted off-site to a monitoring system and/or designated personnel.In this manner, any problems with the self-testing of therescue/evacuation process are immediately brought to the attention ofthe proper personnel who can perform repairs in a timely fashion.

As will be described in detail below, the self-testing of thethree-phase AC back-up power supply includes both an evaluation of thepower supply system itself (including the charge level of the individualbattery cells) and a test of the battery stack under actualrescue/evacuation conditions.

In preferred embodiments of the present invention, the monitoring systemincludes a visual display mounted in a location on the traction elevatorsystem that is used by technicians or others involved in maintenanceactivities.

One exemplary embodiment of the present invention takes the form of amonitoring system for controlling self-testing of a traction elevator,comprising a self-testing process module in communication with athree-phase AC back-up battery power supply and an elevator controlsystem. The self-testing process module includes a processor configuredto initiate and control a series of steps for performing measurements ofthe back-up battery power supply, including measurements of the batterysupply under evacuation/rescue procedures. In accordance with theinvention, the processor is programmed to initiate testing on a definedschedule. The monitoring system also includes a display unit providingvisual information regarding the status of self-testing processes andtheir results, a database in communication with the back-up batterypower supply and the elevator control system (the database storingresults of self-testing processes) and a communications unit fortransmitting test results to a remote maintenance controller.

Other and further embodiments and aspects of the present invention willbecome apparent during the course of the following discussion and byreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings,

FIG. 1 is a simplified block diagram of an exemplary traction elevatormonitoring system for performing self-testing in accordance with theprinciples of the present invention;

FIG. 2 illustrates an exemplary display that may form part of theinventive monitoring system;

FIG. 3 contains a flowchart of an exemplary series of steps that may beused in a given self-testing process; and

FIG. 4 is an isometric view of the components forming the back-up powersupply system.

DETAILED DESCRIPTION

FIG. 1 is a simplified block diagram of an exemplary monitoring system10 formed in accordance with the present invention to perform andcontrol automated self-testing of the emergency operation conditions ofa traction elevator. As mentioned above and outlined in FIG. 1,monitoring system 10 is configured to transmit self-test commands toboth a three-phase AC back-up power supply 20 and elevator controls 30.The commands are transmitted on a pre-programmed, scheduled basis toperform the tests on a regular schedule (perhaps once a week, forexample) at times that are particularly selected to be “low demand”operation times (such as overnight), since the elevator car needs to bedisconnected from the main power supply and taken out of service toperform the testing. In a preferred embodiment, an “override” of thepre-programmed schedule may be used to perform testing by on-locationpersonnel when the need arises.

Monitoring system 10 is shown as including a self-test process module 12that includes software-defined instructions for initializing andcontrolling various self-test operations, and a display unit 14 thatprovides a visual indication of the state of the back-up power supply.In one or more embodiments of the present invention, monitoring system10 may include a database 16 for storing test results and acommunication unit 18 for converting the received test results into awireless signal for communication to a remotely-located maintenancecontrol system and/or other appropriate systems and persons associatedwith maintenance of the traction elevator. Test results may also betransmitted along a “wired” output path to these other remote systems.In the arrangement of FIG. 1, the various components within monitoringsystem 10 communicate via a data bus 11. Results of self-testingoperations from back-up power supply 20 and elevator controls 30 areshown as sent back to monitoring system 10, where they may be stored indatabase 16 and/or transmitted via communication unit 18 to properremotely-located systems and personnel, including transmission to acloud-based maintenance/monitoring system.

Three-phase AC back-up power supply system 20 is shown in this exemplaryembodiment as comprising a stack 22 of four individual battery cells221, 222, 223, and 224. During normal operation, a charging circuit 24(connected to an incoming power bus) is used to maintain an acceptablecharge level on the battery cells. A three-phase AC generator circuit 26is included within back-up power supply 20 and used to convert the DCpower of battery stack 22 into an acceptable three-phase AC output. Acomplete description of the generation of such three-phase AC back-uppower from a supplied battery stack is found in U.S. Pat. No. 9,601,945,assigned to the assignee of this application and herein incorporated byreference.

The self-testing of back-up power supply 20 is two-fold, including amonitoring of the charging level of individual batteries 22 i used tocreate the three-phase AC output power, as well as an evaluation of theperformance of the battery stack under load conditions. Monitoringsystem 10 is configured to manage the charging of batteries 22 viacharging circuit 24, which in this case is used to provide informationto monitoring system 10 regarding the power levels of the individualbatteries 22 i and their performance during a rescue/evacuationprocedure when disconnected from the main power supply.

The purpose of the self-testing is to identify a failed battery 22 _(i)(or complete battery stack 22) or other failed component(s) ofthree-phase AC generator circuit 26 that would otherwise go undetected.For example, an “open” cell 22 _(i) will allow the stack of batteries toread as “charged” on a float charger, but when a load is applied, thevoltage across the stack dramatically drops. The self-test is configuredto look for this drop in voltage and generate a test output signalindicative of the “failed” condition.

It is to be noted that this test is complicated by the presence of asurface charge that develops on the batteries once they are fullycharged. Thus, to avoid unreliable responses, self-test process module12 is preferably configured to disable charging circuit 24 and then runan inverter self-test. Allowing the inverter self-test to run for afixed period of time (for example, about 10 seconds) burns off thissurface charge. Then, after running the inverter self-test for about 10seconds, the voltage of battery stack 22 is measured under loadconditions. After a pause (for a time period of about 10 seconds again),a second measurement of battery voltage under load is made. A change involtage greater than a predetermined amount (for example, more thanabout 2.5 volts) indicates the presence of a failed battery cell 22 _(i)if the second reading is below a defined value (such as 50 vdc).

In preferred embodiments, self-test process module 12 is furtherconfigured to stop battery charging in the event that a failure incharging circuit 24 is recognized. While a normal charger will normallystop charging batteries at about 54 vdc, a charger that has gone into a“failed” condition may unknowingly continue to charge battery cells to alevel well above this voltage, which may result in damage to batterycells 22, or even back-up power supply 20 itself. To prevent thisrun-away charging from occurring, back-up power supply 20 is shown asincluding a disable circuit 28, controlled by self-test process module12, that disables charging system 24 if battery stack 22 becomes chargedabove a preset level (which is itself above the normal “float” chargevoltage of charging system 24).

A feature of the self-testing system of the present invention is theinclusion of a visual display that allows for the appropriate personnelto know the status of a given traction elevator at any point in time. Itis to be understood that any appropriate type of graphical userinterface (GUI) may be used to form this display. FIG. 2 is a diagram ofan exemplary display unit 14, with the understanding that the details ofthe included indicators may vary in their presentation and organization.In the particular design shown in FIG. 2, display unit 14 includes anLCD 40 that provides an alpha-numeric indication of the current “state”of back-up power supply 20. For example, “EPS TESTING” may be displayedduring an automated self-test cycle as triggered by self-test processmodule 12 (an associated LED 48, defined below, is lit when testingbegins). In this particular arrangement, display unit 14 includes adiagnostic LED bank utilized for trouble-shooting, with various LEDsenergized upon the recognition of various “warning” conditions. In thisembodiment, a first LED 42 is associated with the presence of a “lowbattery” condition (LOB) of a given battery cell, as detected during aself-testing cycle. First LED 42 is illuminated when the reserve batterysupply drops below a predetermined float value. It is to be understoodthat in a preferred embodiment of the present invention, these warningsare also transmitted to maintenance personnel as described above.

Also included in display 14 of FIG. 2 is a third LED 46 that isassociated with the charging process of battery stack 22. In particular,when battery stack 22 is being charged from the main power supply (anormal operation condition), third LED 46 is lit to show the state of“active charging” (“CHG”). In an exemplary configuration, third LED 46may be designed to cycle on/off during this active charging period untilthe charge is above a predetermined float voltage level. LCD 40 maydisplay a message such as “BATTS CHARGING” while this is taking place.Once the float voltage is reached, third LED 46 remains steady “on” andLCD 40 displays an updated message such as “BATTERIES CHARGED”. It is tobe understood that if a power loss occurs in the building during acharging cycle, the charging will be halted and a “LOW BATTERY” messagepreferably shown on LCD unit 40. Under these circumstances first LED 42will turn “on”. If a fault occurs during the self-test, second LED 44will light and an appropriate message will be displayed on LCD 40.Again, these various conditions may be transmitted via wired or wirelesscommunication links from monitoring system 10 to appropriate maintenancepersonnel.

Upon restoration of building power, charging circuit 24 resumes theprocess of recharging battery stack 22, clearing the “LOW BATTERY”condition. The LOB reset level is typically set by circuitry withincircuit 24 (i.e., hardcoded in software), where a value of 50 vdc istypical. When the battery voltage is above the adjustable LOB trippoint, but has not yet reached the fixed LOB reset point, alarm LED 48may be configured to flash on/off, indicating that the charging processis within the LOB recovery hysteresis loop.

In accordance with the principles of the present invention, theself-testing process may be extended beyond the testing of thethree-phase AC back-up power supply itself to include testing theemergency rescue/evacuation procedures performed by the elevator car(i.e., the actions of the car necessary to provide an evacuation in thecase of a power failure). FIG. 3 is a flow chart of an exemplary processof the present invention that is implemented via self-test module 12 toprovide both three-phase AC back-up power supply testing and elevatorcar evacuation testing.

As shown, an exemplary self-testing process begins at step 100 with arequest to “initiate” the self-testing process. The request is generatedby self-test process module 12 and is typically pre-programmed to occurat a given time in a predetermined schedule. For example, the test maybe performed once a week (or perhaps once a month) during a low usageperiod. It is contemplated that daily self-testing is not typicallynecessary and may have the unintended result of reducing batterycapacity.

Upon initiation, self-test process module 12 transmits a command toelevator mechanical controls 30 to move the elevator car to a designatedbetween-floor location that is used for self-testing. At this point, theelevator car is designated as “out of service”, which may be shown as amessage on display unit 14. Once the elevator car is in place, self-testprocess module 12 transmits a command to three-phase AC back-up powersupply 20 to initiate the battery testing process (step 120). Thisfollows by disconnecting the elevator from the main power supply (step130) and coupling the battery supply to the elevator controls.Measurements of three-phase AC power under rescue/evacuation conditionsare made (step 140), which may include the sub-steps of burn-off andre-testing, as described above.

In the particular process as outlined in FIG. 3, the next step is acheck to see if an elevator car rescue/evacuation process is to beincluded in the self-test (step 150). As mentioned above, theavailability of full three-phase AC power during rescue/evacuation of atraction element is a preferred arrangement for allowing the car toquickly move to the optimum floor location, stop, and open the doors.

If the response to the elevator car testing query is “no”, the processcontinues with the final steps as will be discussed below. Presuming theresponse is “yes”, the process moves to step 160 and initiates elevatormechanical controls 30 to perform a rescue/evacuation routine. The driveis switched to a non-line regenerative mode and the elevator system to“test” mode, energized only by the three-phase AC back-up battery powerNext, the “lightest” direction is determined for movement of the car tothe nearest floor (step 162), and the car is moved at rescue (slow)speed to nearest floor (step 164). The elevator car goes through aleveling process (step 166) and energizes the door motors to cyclethrough an “open/closed” sequence (step 168). Once completed, the carremains at this “floor” location and the process returns to the mainflow, step 170, which measures the battery level (voltage and charge) ofback-up power supply system 20 to confirm that the post-testing powersupply is still sufficient to execute an actual emergency process.

At this point, self-test process module 12 receives an indication thatthe self-test process is complete (step 180), and the elevator isre-connected to the main power supply (190). The results of the testingare logged (step 200), and perhaps stored on-board within database 16 ofmonitoring system 10. As mentioned above, the test results may also becommunicated to a remotely-located maintenance system (including acloud-based system which may then, in turn, relay the messages toappropriate personnel).

Advantageously, the transmission of results directly to a technician canprovide alerts of a battery failure, low battery, mechanical problemswith car control mechanisms, and the like. Preferably, the test resultsinclude an estimate of the number of sequential rescue/evacuation testsequences can be run without recharging the back-up power supply. Thisinformation is also an indication of when it is time to replace thebatteries. In an alternative approach, the battery type and voltagehistory during the rescue/evacuation could be provided to the elevatorcontroller and then sent to an AI program to determine when to replacethe batteries. Thus, instead of relying upon theoretically calculatedpower values (as was done in the past), the generation of the actual,measured battery back-up power required to perform the rescue/evacuationprocedures may be used to provide not only immediate power capabilities,but trended to provide information regarding its capability to performfuture rescues.

FIG. 4 is an isometric view of three-phase AC back-up power supply 20 aspackaged within a housing 50. Advantageously, the modular nature ofback-up power supply 20 allows for easy access to (and replacement of,if necessary) individual elements. The particular configuration ofhousing 50 as shown in FIG. 4 includes an interior shelf 52, withdisplay 14 and a pair of batteries from the stack (here, batteries 22 ₁and 22 ₃) disposed on this shelf. A remaining pair of batteries 22 ₂ and22 ₄, as well as main power switch/circuit breaker 27, are disposed onthe lower shelf. In this particular arrangement, self-test processmodule 12 of monitoring system 10 interacts with a circuit board 54 thatsupports charging circuit 24 and three-phase AC generator circuit 26,where circuit board 54 is positioned behind batteries 22 along a rearwall 56 of housing 50.

The foregoing description for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that specificdetails are not required in order to practice the invention in itsbroadest configuration. Thus, the foregoing descriptions of specificembodiments of the invention are presented for purposes of illustrationand description. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed; obviously, many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, they therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated. It is intended that the following claimsand their equivalents define the scope of the invention.

What is claimed is:
 1. A monitoring system for controlling self-testingof a rescue/evacuation system for a traction elevator, comprising: aself-testing process module in communication with a three-phase ACback-up battery power supply and an elevator control system, theself-testing process module including a processor configured to initiateand control a series of steps for performing measurements of thethree-phase AC back-up battery power supply, including measurements ofthe battery supply under an AC load of an elevator car underrescue/evacuation conditions as performed by the elevator controlsystem, wherein the processor is programmed to initiate testing on adefined schedule, a display unit providing visual information regardinga status of self-testing processes and their results; a database incommunication with the three-phase AC back-up battery power supply andthe elevator control system, the database storing results ofself-testing processes; and a communications unit for transmitting testresults to a remote maintenance system.
 2. The monitoring system asdefined in claim 1 wherein the monitoring system further comprises adata bus for establishing a communication link between each of theself-testing process module, the display unit, the database, and thecommunications unit.
 3. The monitoring system as defined in claim 1wherein the communications unit is configured to transmit test resultsto a cloud-based remote maintenance system, the test results includingrequests for replacement/repair items as necessary.
 4. The monitoringsystem as defined in claim 1 wherein a wireless transmission medium isused to communicate with the remote maintenance system.
 5. Themonitoring system as defined in claim 1 wherein the display unit takesthe form of a graphical user interface.
 6. The monitoring system asdefined in claim 1 wherein the display unit comprises an alpha-numericdisplay for presenting selected messages identifying testing proceduresand results; and a plurality of indicator lamps associated with separatetrouble-shooting conditions.
 7. The monitoring system as defined inclaim 1 wherein the self-testing of the rescue/evacuation systemincludes energizing all components of the elevator control system withthe three-phase AC back-up battery power supply to perform a rescueoperation to move the elevator car to a floor, and an evacuationoperation by opening and closing elevator doors.
 8. The monitoringsystem as defined in claim 1 wherein the self-test process module isfurther configured to monitor battery charging processes during normaloperation.
 9. The monitoring system as defined in claim 8 wherein theself-test process module monitors performance of a battery chargerincluded within the three-phase AC back-up battery power supply.
 10. Themonitoring system as defined in claim 1 wherein the self-testing of theelevator car includes utilizing a plurality of three-phase AC back-upbattery power measurements associated with multiple rescue/evacuationoperations and collected over time to predict performance requirementsand capabilities of the three-phase AC back-up battery power supplyduring future rescue operations.